Ventricular Tachycardia

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Ventricular tachycardia (VT) can be difficult to differentiate from supraventricular tachycardia with aberrancy. When in doubt, it is safest to treat most wide complex tachycardia as VT. Up to 80% of cases of all WCT are ventricular tachycardia, and none of the available algorithms perform well in the acute setting. One should be cautious of treating potential VT with atrioventricular nodal blockers (as one would for SVT).

 

VT vs SVT with Aberrancy – the CRAM Mnemonic. This mnemonic is adapted from the Brugada algorithm, which is one of several algorithms to help differentiate between supraventricular tachycardia with aberrancy and ventricular tachycardia. Concordance describes the situation where QRS complexes are in the same direction (up or down) across the entire precordium (V1 – V6); if this condition is met, ventricular tachycardia is diagnosed. If the beginning of the R wave to the nadir of the S is greater than 100 ms, ventricular tachycardia is diagnosed. If there are signs of AV dissociation (i.e., capture beats, fusion beats, or occasionally P waves can be visualized), ventricular tachycardia is diagnosed. Finally, if the previous three criteria are not met and the morphology suggests aberrancy then ventricular tachycardia is unlikely. Rsr’ appearance (as opposed to rsR’) in V1 strongly favors ventricular tachycardia. AV, atrioventricular.

Examples

ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

The presence of a narrow capture beat about 1/3 of the way through the rhythm strip confirms atrioventricular dissociation - a criterion that indicates ventricular tachycardia. (The vertical green bars can be ignored).
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

The "northwest" axis strongly favors ventricular tachycardia.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

The right bundle branch block pattern with the first R larger than the r' in V1 is very specific for ventricular tachycardia.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

Josephson's sign, notching near the nadir of the S wave, can be seen in V1 and V2, and suggests ventricular tachycardia. This patient was ultimately diagnosed with ventricular tachycardia.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

Run of nonsustained ventricular tachycardia in a patient with known hypertrophic cardiomyopathy.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

Although the rate is slower than typical ventricular tachycardia, features favoring ventricular tachycardia include RSr' (left "bunny ear" taller than the right one in V1) and northwest axis. This rhythm was confirmed to be ventricular tachycardia by electrophysiology and the patient was electrically cardioverted.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

Features that favor ventricular tachycardia include R-S time greater than 100 ms.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

Ventricular tachycardia is favored given concordance of the complexes across the precordium (i.e., all the QRS complexes are going in the same direction) and the presence of Josephson's sign - notching of the S wave near its nadir - best seen in the inferior leads (II, III, aVF).
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

Negative QRS concordance across the precordium (i.e. QRS complexes are all pointing downward) strongly favors ventricular tachycardia. This patient was unstable and was electrically cardioverted. A post-cardioversion ECG showed anterior ST-elevation and left heart catheterization revealed a left anterior descending artery occlusion.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

This regular, wide complex tachycardia is concordant across all precordial leads (i.e., the QRS complexes are going in the same direction - downwards), confirming ventricular tachycardia. The patient was electrically cardioverted.
ECG Showing Ventricular Tachycardia

Ventricular Tachycardia

Ventricular tachycardia can exist in slower-than-expected rates (<120 bpm) in the elderly population and in those on antiarrhythmics like amiodarone. Features that suggest ventricular tachycardia include a right bundle branch block pattern with the first R larger in amplitude than the second r' in V1, and a fusion beat. This patient had an implantable cardioverter defibrillator that did not recognize the rhythm due to the slow rate. The patient was confirmed to have ventricular tachycardia via an electrophysiology study.

References

  1. Vereckei A. Current Algorithms for the Diagnosis of wide QRS Complex Tachycardias. Current Cardiology Reviews. 2014;10(3):262-276.
  2. Baxi RP, Hart KW, Vereckei A, et al. Vereckei criteria as a diagnostic tool amongst emergency medicine residents to distinguish between ventricular tachycardia and supra-ventricular tachycardia with aberrancy. Journal of Cardiology. 2012;59(3):307-312.
  3. Szelényi Z, Duray G, Katona G, et al. Comparison of the “real-life” diagnostic value of two recently published electrocardiogram methods for the differential diagnosis of wide QRS complex tachycardias. Academic Emergency Medicine. 2013;20(11):1121-1130.
  4. Moccetti F, Yadava M, Latifi Y, et al. Simplified Integrated Clinical and Electrocardiographic Algorithm for Differentiation of Wide QRS Complex Tachycardia: The Basel Algorithm. JACC Clin Electrophysiol. 2022;8(7):831-839. doi:10.1016/J.JACEP.2022.03.017